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Inaccurate Boost Gauge

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Old 10-29-2008, 05:50 PM
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Default Inaccurate Boost Gauge

So, I just turboed my car and installed a Prosport Boost gauge. When I had it tuned, the tuner said the gauge was not reading correcting (which I guessed becasue it was reading 28psi vaccuum at idle, from what I understand is high).

I have checked and zipped tied all the vaccum hoses. I did notice that my e-brake light is on all the time now (gets brighter when I pull the e-brake up). Also, last night, I noticed that when I pull the e-brake up, the guage tacks to 30. So I'm starting to wonder if it has something to do with how I installed it.

Anyone ever have a similar issue?
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Old 10-29-2008, 06:01 PM
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what line did you tap into? brake booster line?

the line you want to tap into is the vac line that runs to the left side of the throttle body.
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Old 10-29-2008, 06:04 PM
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Sorry, I left that out. I tapped the regulator line comming out of the throttle body.

I feel like it has something to do with the e-brake, but I am unsure why.

It might be the power line i used for the sender unit (electrical guage), it was off someting in that area (will take a look to exactly what after work).
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Old 10-29-2008, 07:46 PM
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^^that could affect it.. maybe not a consistant current or something.. just get a fuse adapter and tap off that.
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Old 10-29-2008, 07:57 PM
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I think I will try that this weekend. Hopefully, it'll fix the gauge accuracy and my constant brake light both.
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Old 10-29-2008, 07:59 PM
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im almost certain that tapping into your ebrake line impopperly will cause this issue.
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Old 10-29-2008, 08:22 PM
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Cool. Will give it a try and let you know how it goes.
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Old 10-29-2008, 08:25 PM
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Sweet! good luck!
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Old 10-30-2008, 09:20 AM
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lol looks like you tapped to the ebrake wire that sets the ebrake light on your dash.. check on that like what java said, I dont think its something to do with your vacuum lines
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Old 10-30-2008, 02:02 PM
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Yeah I think it is. It was just right there, so i figued why not (probably should ahve figued out what I was tapping before i did it). Wiring is still very new to me.

The plan is to look at that and put int he black box this weekend. Supposed to be 65, so might ahve a decent day for it.
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Old 10-30-2008, 05:09 PM
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Watching
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Old 10-30-2008, 05:15 PM
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I used my cigarette lighter to power the guages. I completely deleted the cig lighter and just used that as a power and ground for the gauges. Had to change from 10A to 15A (gauges drew more current than the lighter), but other than that, I had no problems with it.
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Old 10-30-2008, 05:32 PM
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I think the issue with the accuracy has to do with the power source for the sender unit in the engine bay.

I also used the cigarette lighter to power my gauges, though. Which I think has caused some kinda of issue as I tried to use a phone charger and it turned my Prosports from orange when the lights are on to white (setup to be white when lights are off and orange with lights by connecting a white to constant power and orange to an alternating (light switch)). I ran both the power and the white wire to the cigaretee lighter wire. Maybe, not enough power with the cigarettee ligher in use? I didn't put a higher fuse in it either (left it at 10A).

Less concerned about this issue, but would like to figure it out as well.
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Old 10-30-2008, 05:35 PM
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That's why I completely deleted that outlet. I cut the wires off the connector for the lighter, and hooked the gauges directly up to the wires. If you use the lighter, it's going to add a load to the circuit, resulting in a higher amp draw.
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Old 10-30-2008, 05:47 PM
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Yeah. Probably will rewire those with a fuse cut in thing (forgoet what their called), when I get the time. Right now, for now I can use the lighter in the arm rest (although it is a pain to get to).
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Old 10-30-2008, 05:50 PM
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Yeah, the cig light delete worked out nicely. I didn't have to tap into anything, didn't have to add another circuit, nothing. Just connect and go.

Also, for the Prosports, if you got the Premium Peak gauges, make sure you connect the red (might be wrong on the color) to a 12V source. I didn't do that and I can't set the peak value on my gauges. I'm going to change that tomorrow though. If it doesn't have constant 12V for that wire, it will forget the peak value and reset.

Q: I tried that but each time I turn the car off/on it comes back?
A: You do not have the Red wire connect to 12v CONSTANT power. That is what holds memory. White and orange wires go to ignition/accessory power or headlight switch depending on the lighting result you want.
Just a heads up, because I didn't know about that
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Old 10-30-2008, 08:26 PM
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Thanks for the tipe, but i got the performance (i think). The lower grade (no other funtionalities).
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Old 10-31-2008, 01:15 PM
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So new development: The gauge appeaers to become accurate when driving sometimes (in and out of bumps). Makes me think more that it is a vacuum leak now. Maybe can do with a loose electrical connection?

What should my vaccum be at idle again (lie 20 psi right?)
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Old 10-31-2008, 04:27 PM
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your car shouldnt be at any psi level when in vacuum.. or may you meant 20 mmhg?
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Old 10-31-2008, 04:30 PM
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I'm sorry, but what does mmhg stand for?

Basicly, I'm refering to the bottom half of the guage (under 0 PSI Boost).
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